TPS61000, TPS61001, TPS61002, TPS61003, TPS61004, TPS61005, TPS61006, TPS61007

SINGLE- AND DUAL-CELL BOOST CONVERTER WITH START-UP INTO FULL LOAD

SLVS279C – MARCH 2000 – REVISED APRIL 2003

16

POST OFFICE BOX 655303

APPLICATION INFORMATION

With those parameters it is possible to calculate the value for the inductor:

L

+

V

BAT

x V

OUT

– V

BAT

∆I

L

xfx V

OUT

(4)

Parameter f is the switching frequency and

In this example, the desired inductor has the value of 12

µH. With this calculated value and the calculated cur-

rents, it is possible to chose a suitable inductor. Care has to be taken that load transients and losses in the circuit

can lead to higher currents as estimated in equation 3. Also, the losses in the inductor caused by magnetic hys-

teresis losses and copper losses are a major parameter for total circuit efficiency.

The following inductors from different suppliers were tested. All work with the TPS6100x converter within their

specified parameters:

Table 1. Recommended Inductors

VENDOR

PART NUMBER

Coilcraft

DO1608P Series

DS1608P Series

DO3308 Series

Coiltronics

UP1B Series

UP2B Series

Murata

LQH3N Series

Sumida

CD43 Series

CD54 Series

CDR74B Series

TDK

NLC453232T Series

capacitor selection

The major parameter necessary to define the output capacitor is the maximum allowed output voltage ripple of

the converter. This ripple is determined by two parameters of the capacitor, the capacitance and the ESR. It is

possible to calculate the minimum capacitance needed for the defined ripple, supposing that the ESR is zero.

C

min +

I

OUT

x V

OUT

– V

BAT

fx

∆VxV

OUT

(5)

Parameter f is the switching frequency and

∆V is the maximum allowed ripple.

With a chosen ripple voltage of 15 mV, a minimum capacitance of 10

µF is needed. The total ripple will be larger

due to the ESR of the output capacitor. This additional component of the ripple can be calculated using the fol-

lowing equation:

∆V

ESR +

I

OUT

xR

ESR

(6)